The invention relates to a plowing device with a plow chain.
Coal plows are used in underground mining for shearing off coal. The drive is carried out by a pulling member in form of a plow chain, which moves the coal plow back and forth on a longwall parallel to a coal face of a seam between two tracks. The mined debris and coal are transported by a chain scraper conveyor. The chain scraper conveyors are simultaneously guide, roadway and abutment for the coal plow. The plow chain itself is guided and supported in corresponding channels of the plow chain guide.
The plow chain is subject to severe stress in use. In addition to intense tensile and impact loads, there is high friction. This occurs mainly within the channels and deflection zones. The consequent high wear of the individual chain links and of the chain locks which connect the plow chain is countered with different cross sections of the chain links.
EP 1 495 239 B1 describes a plow chain train with a chain lock link guided inside channels. The chain links located ahead of the chain lock links are hereby formed as special chain links and have thickened regions on their chain limbs which extend parallel to the longitudinal direction of the plow chain train, to protect the chain lock link. As a result, the chain lock link is protected from premature wear.
Against the background of increasingly higher powers and speeds to be transmitted, also this construction offers, based on all chain links of a plow chain, potential for improvement. In particular, the friction caused by the contact of the chain links and channels results in addition to corresponding friction losses to a rapid local heating of the edge layer of the individual chain links above the austenitizing temperature of the material. The heating is followed at standstill or free running by an equally rapid cooling, by which friction martensite can form. Thus, in addition to the friction wear of the plow chain, additional crack formation can occur which weakens stress resistance of the individual chain links. The cracks lead to stress peaks and to a premature failure and thus to a costly shutdown of the entire plowing device.